Charles a



(No Model.)

G. A. TIMME. ELECTRIC DENTAL EURNAGE.

No. 589,048. Patented Aug. 31,1897.

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UNITED STATES PATENT EEICE.

CHARLES A. TIMME, OF NE\V YORK, N'. Y.

ELECTRIC DENTAL FU RNACE.

SPECIFICATION forming part of Letters Patent No. 589,048, dated August31, 1897.

Application filed March 14, 1896.

To all whom t may concern:

Be it known that l, CHARLES A. TIMME, a citizen of the United States,residing in the city of New York, in the'county and State of New York,have invented certain new and useful Improvements in Electric DentalFurnaces, of which the following is a specification.

This invention relates to an improved electric dental furnace whichisintended for use in the manufacture of artificial teeth, bridgework,and gums, and in which the high degree of heat necessary for the bakingof the articles and the melting of the enamel on the same is producedbythe electric current that is supplied to suitable heating platesarranged in the walls of the muiiie and the invention consists of anelectric dental furnace which is composed of an exterior casing ofrefractory material, removable heating-plates arranged at the interiorof the inutile, the plates being independently connected with avsuitable source of electricity, so that ditferent degrees of heat can beproduced at the interior of the muttle, according to the work to be donein the same.

In the accompanying drawings, Figure l. represents a perspective View ofmy electric dental furnace. Fig. 2 is a plan view, partly in horizontalsection, on line 2 2, Fig. l; and Fig. 3 is a vertical transversesection on line 3 3, Fig. 2.

y Similar letters of reference indicate corresponding parts.

Referring to the drawings, A represents the base of myimproved electricdental furnace, which is made either of refractory material or ofsuitable metal, and which is provided at its rear part with an uprightflange a, that extends along three sides of the base A. A mulile B issupported on the base A and arranged so as to abut against the flange a.rlhe muftle B is made of suitable refractory material, preferably ofrectangular shape, and provided at its inside with electricheatingplates C C,which are supported at the top and bottom of the munieand separated from the walls of the same by a layer c of non-conductingmaterial. The electric heating-plates C C are each formed of refractorymaterial, in which a platinum conducting-wire in serpentine form isembedded while the material is Serial No. 583,158. (No model.)

in plastic state. The top and bottom plates may be supported on suitableiianges el d, so as to be readily removed from the muftie for beingexchanged or repaired. The side walls may also be provided with similarelectric heating-plates D D, as shown in dotted lines in Fig. 23, sothat the temperature that is desired to be produced in the muttle can beincreased or decreased in whole or at any particular part, according asone, two, or more plates are switched intocireuit. The bottom plate Oserves as a support for the objects to be burned in the mut'tle, such asartificial teeth, bridge-work, gums, rbc., made from porcelain and othersubstances.

B y arranging the electric heating-plates independently of the inutileat the inside of the same, the heat of the same is enabled to actdirectly on the objects to be burned, while at theV same time thetemperature in the mut'tie can be raised or lowered by switching in allor aportion of the plates, or the heat can be applied to one or moresides ofthe objects by switching the upper conducting-plate alone or theside heating-plates, or the upper, side, and bottom plates into thecircuit. This arrangement has the advantage that not only the Aheat inthe muttle can be easily regulated, but that larger objects, such asartificial gums, can be burned in the muiiie and provided with thickeror thinner coatings of enamel, which can be burned on the objects inavery effective manner.

The front opening of the mutlie is closed by a cover B', which isprovided with a free packing of insulating material, said coverbeingprovided with exterior stays b, so that it can be supported incontact with the front edges of the mut'tie. The cover B is furtherprovided with a peep-opening h2, closed by a suitable plug b3.

The front part of the 1n ut'tle B is surrounded by two metallic strapsff', of which one is provided at one side with two binding-posts f2 andVat the opposite side with one main binding-post F, while the secondstrap is provided at one side with one main binding-post F and at theother side with two bindingposts f". The current is supplied tothe mainbinding-post F and conducted by the strap f over the binding-posts f2 tothe wires of the heating-plates C C', if both are used, or the IOO f2,respectively.

one or the other only, according as either the top or bottom platesalone is used, in which vlatter case the ends of conducting-wires arereleased from the upper or lower binding-post The current is conductedalong the wires embedded in the plates C C/ and heats said plates toincandescence, passing to the binding-postsf3, strap f, and mainbinding-post F' back to the battery or other source of electricity. Bythe electric connection of the main wires with the main binding-postsand of the auxiliary binding-posts with the wires in the plates C C anyone of the heating-plates can be readily placed in circuit and therebythe required degree of heat produced at the interior of the muffle.

lIn case interior heating-platesare used at the side walls of the mufiiein addition to the top and bottom plates additional binding-posts forthe side plates have to be arranged,- to which the ends of the platinumwires are applied, asjffon the stripf,and]C6 andf7 on theconducting-strip f', and which are switched into circuit with the mainbinding-posts, through which the current is supplied. When the burningof the articles in the muffle is completed, the cover is removed, sothat access is given to the articles in the mufiie. In case any one ofthe heating-plates should become defective it can be readily removedfrom c the muffle and either replaced by a new heating-plate or repairedby locating the break in the wire and reconnecting the same. By

muffle to the manufacturer for repairs, which is the case when theconducting-wires are embedded in the walls of the muffle itself, inwhich case it is difficult to locate the break and the use of the mufflerendered impossible until the break has been repaired. This may lead toannoying delays in the work on hand, which is obviated by myilnprovedconstruction, in which the dentist can readily substitute a newconducting-plate for a vdefective plate and continue thereby the use ofthe muflic.

The baking of the dental plates is effected 5o ata temperature of 3,5000Fahrenheit or more, and the heating-plates are capable of withstandingsuch degree of heat.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is-

In an electric dental furnace, the combination of a inufie composed ofrefractory material, removable independent heating-plates disposed inthe walls of said mufe, and composed of refractory material havingconductors embedded therein, two separate conductive straps surroundingsaid muiiie near its front end, each provided with a plurality ofbinding` posts for establishing connection with the electric source andwith the heatingplates independently of each other.

In testimony that I claim the foregoing as my invention I have signed myname in presence of two subscribing witnesses.

CHARLES A. TIMME.

Witnesses:

PAUL GOEPEL, GEO. W. JAEKEL.

